Online fashion retailer Asos has withdrawn a batch of metal-studded belts from sale after they were found to be radioactive.

The leather belts could cause injury to the wearer if worn for more than 500 hours and are being held in a radioactive storage facility after testing positive for Cobalt-60, according to an internal report by the retailer.

The report, called Project Purple Flower and seen by the Guardian, said one of the brass-studded belts was pulled by US border control and tested positive.

It led to a worldwide recall of the items, with 49 sold across 14 countries, but it is not known how many have been returned.

An Asos spokesman said today that the belts were recalled at the beginning of this year and all those who had bought them had been contacted.

According to the Guardian, the report said: "None of these belts are suitable for public use or possession."

It added: "Unfortunately, this incident is quite a common occurrence. India and the far east are large consumers of scrap metal for their home and foreign markets.

"During the refining process of these metals, orphaned radioactive sources are sometimes accidentally melted at the same time. This in turn (contaminates the process) and traps the radioactivity in the metal as an alloy or in suspension."

A spokesman for Asos said: "A product supplied to Asos did not meet UK health and safety standards. Asos worked with all relevant authorities and undertook a precautionary product recall, in line with our high standards of quality and customer care. No other Asos product lines are affected.

"Asos continues to work with the relevant regulatory authorities and is in dialogue with the supplier and the factory workers involved to ensure a satisfactory outcome."

The Guardian also reported that Faizan Haq, head of Haq International, the company named as the supplier of the belts by Asos, has been refused permission to inspect the goods.

But the Asos spokesman said it had also been restricted from inspecting the belts due to "standard regulatory procedure" on the part of US authorities.